title: Kinetics and dynamics in physisorption of CH3Cl on HOPG: surface temperature and molecular orientation dependence.
abstract: We report a study of kinetics and dynamics in physisorption of CH(3)Cl on a highly-oriented pyrolytic graphite (HOPG). Thermal energy atom scattering (TEAS) was used to probe the kinetics of thermal CH(3)Cl adsorption on HOPG during the coverage evolution. The desorption energy of CH(3)Cl on HOPG changes from 0.25 to 0.30 eV with increasing surface coverage, suggesting the attractive interaction between CH(3)Cl molecules on the surface. On the other hand, the oriented molecular beam scattering was used to monitor the dynamical interaction of CH(3)Cl with HOPG at zero coverage, demonstrating that the CH(3)Cl scattering intensity depends on the molecular orientation of the incident CH(3)Cl. The observed steric preference is not sensitive to the surface temperature. These results suggest that the moderate anisotropy in the interaction potential induces the molecular-orientation dependence of energy dissipation during the transient trapping into the physisorption well.
authors.affiliation: Renovation Center of Instruments for Science Education and Technology, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan. mitihiro@cw.osaka-u.ac.jp
authors.forename: Michihiro
authors.initials: M
authors.lastname: Hashinokuchi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Fukuyama
authors.forename: Michio
authors.initials: M
authors.lastname: Okada
authors.forename: Toshio
authors.initials: T
authors.lastname: Kasai